Case Fatality Rates, Mortality, and R-naught

Case Fatality Rates, Mortality, and R-naught, by Peter Negrea and Emma Barhydt

Health officials use statistics to grasp the magnitude of situations like the one with which we are currently faced. In the coming weeks and months, we will likely hear references to terms such as “mortality rate” and “R-0” (pronounced R-naught) more and more often.

Mortality rate is mostly self-explanatory: of those infected, what percentage will succumb to the disease? Currently, the World Health Organization (WHO) claims the mortality rate is 3.4%, but that number may be artificially inflated as it does not take into account the many mild cases whose carriers have not been tested due to showing mild symptoms or none at all. It is worth noting that this number will change as time goes on and more data is gathered. We hope that as medical professionals learn more about the disease and determine effective treatments they will be able to adequately care for more severe and critical cases, further lowering the mortality rate. We can do our part to lower the mortality rate by boosting our immune systems, avoid getting infected, and avoid infecting others for as long as possible.

R-0 (R-naught) is a measure of the rate at which the virus spreads. Specifically, it is the average number of people to which an infected person will pass the disease. Most estimates by peer-reviewed medical editorials place the R-0 of COVID-19 between 2-3, with several studies settling on 2.28. It is important to understand that this is a mathematical figure based on current data and not an iron-clad fact about the virus. Statisticians can use different methods and reach slightly different results, which is the reason why there is no single R-0 agreed upon number. R-0 is also a number that can change with human behavior. As people realize the severity of the pandemic and implement voluntary or imposed social distancing, the spread of the disease will slow down, which will therefore lower the R-0. The goal is to reduce the R-0 to less than 1, which means that on average, every infected person will pass the disease to less than one other person. This will indicate that the pandemic has already passed the peak number of infections at one time and is on the

According to a study done by the Chinese Center for Disease Control of over 70,000 cases, while COVID-19 is less lethal than the closely related SARS-CoV and MERS-CoV, it is also more contagious. 1.2% of COVID-19 cases presented no symptoms (were asymptomatic), 81% of cases were mild, and 17.8% of cases were considered severe or critical. Of all the cases studied, the mortality rate was 2.3%. Of those deaths, the age group most affected has been over the age of 60 and/or those with pre-existing conditions such as hypertension, cardiovascular disease, and diabetes. The fatality rate is highest among “critical” cases, with 49% being fatal after being considered “critical.” According to this study, there have been no deaths in those with mild symptoms. For most, COVID-19 cases will present like the common cold.

That is both good and bad news. The good news is that for most it should feel more like a minor inconvenience than a severe illness. The bad news is that people with mild cases may be spreading the disease without even realizing it. This leads to community spread. Working together, we can prevent community spread so that our more vulnerable neighbors are not infected. Even if you have no symptoms or mild symptoms, plan for the worst. If you assume that you may be spreading the virus, you will be more careful.

First: wash your hands often! This cannot be stated enough, this is the community’s first line of defense. Wash your hands often with soap and warm water for at least 20 seconds (see the back page for ways to time yourself) and thoroughly dry your hands, especially after blowing your nose, coughing, sneezing, or visiting a public place. If soap and water are not readily available, use a hand sanitizer. Cover the entire surface of your hands and rub them together until they feel dry.  Avoid touching your eyes, nose, and mouth. We touch our faces up to 90 times per day without even realizing it. Along with close contact with an infected person, this is how individuals are most likely to become infected.

Whenever you touch a surface such as a doorknob, handrail, elevator button, or even money, you are exchanging microbes that then rest on your hands. For COVID-19, these microbes will primarily enter your body through your eyes, nose and mouth. If you avoid touching your face with hands that have picked up the virus throughout the day, you can avoid the infection.

A good way to break the habit of constantly touching your face is to put a rubber band on your wrist. Every time you catch yourself touching your face, lightly pull the rubber band and snap it against your wrist. That little rubber band might just keep you healthy.

Avoid close contact with anyone who is sick and try to stay six feet away from others when in public. The CDC is urging people not to stockpile facemasks, as regular face masks available to the public will not help to stop the spread of COVID-19. According to multiple scientific studies, more specialized masks and respirators can help, but only if the person wearing it is properly trained in how to wear it. Stockpiling these masks causes a shortage for healthcare practitioners and first responders who are both properly trained in how to use them and need them to treat patients.

In the event that you do become sick, here are steps you can take to avoid spreading the virus to others. Stay home unless you need to receive medical care.Always Cover Your Coughs and Sneezes. Cover your mouth and nose with a tissue when you cough or sneeze or use the inside of your elbow. Throw used tissues in the trash. Use anti-viral tissues if possible.
Immediately wash your hands with soap and water for at least 20 seconds. If soap and water are not readily available, clean your hands with a hand sanitizer that contains at least 60% alcohol. Clean AND disinfect frequently touched surfaces daily. This includes tables, doorknobs, light switches, countertops, handles, desks, phones, keyboards, toilets, faucets, and sinks. If surfaces are dirty, clean them: Use detergent or soap and water prior to disinfection.

Being overly cautious today will prevent more problems tomorrow.

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